From: Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Maxim Kokryashkin <m.kokryashkin@tarantool.org>, Igor Munkin <imun@tarantool.org>, Sergey Bronnikov <sergeyb@tarantool.org> Cc: tarantool-patches@dev.tarantool.org Subject: [Tarantool-patches] [PATCH luajit] FFI: Fix pragma push stack limit check and throw on overflow. Date: Wed, 8 Nov 2023 11:40:44 +0300 [thread overview] Message-ID: <20231108084044.6654-1-skaplun@tarantool.org> (raw) From: Mike Pall <mike> Reported by Sergey Kaplun. (cherry-picked from commit 433d7e8d8d182f44e88b5cfdc4b2d3026469dfb7) `cp->packstack` is the array of size `CPARSE_MAX_PACKSTACK` (7). Before the patch, `cp->curpack` is checked to be less than `CPARSE_MAX_PACKSTACK`, but then `cp->packstack` is accessed at `cp->curpack + 1`, which is out of bounds, so `cp->curpack` value is overwritten. This patch fixes a condition and also adds the error throw when counter is overflow (instead of rewriting a top `cp->packstack` value). Sergey Kaplun: * added the description and the test for the problem Resolves tarantool/tarantool#9339 Part of tarantool/tarantool#9145 --- Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1114-ffi-pragma-pack Tarantool PR: https://github.com/tarantool/tarantool/pull/9342 Relate issues: * https://github.com/LuaJIT/LuaJIT/issues/1114 * https://github.com/tarantool/tarantool/issues/9339 * https://github.com/tarantool/tarantool/issues/9145 src/lj_cparse.c | 4 +- .../lj-1114-ffi-pragma-pack.test.lua | 44 +++++++++++++++++++ 2 files changed, 47 insertions(+), 1 deletion(-) create mode 100644 test/tarantool-tests/lj-1114-ffi-pragma-pack.test.lua diff --git a/src/lj_cparse.c b/src/lj_cparse.c index 6d9490ca..01deb3bf 100644 --- a/src/lj_cparse.c +++ b/src/lj_cparse.c @@ -1777,9 +1777,11 @@ static void cp_pragma(CPState *cp, BCLine pragmaline) cp_check(cp, '('); if (cp->tok == CTOK_IDENT) { if (cp_str_is(cp->str, "push")) { - if (cp->curpack < CPARSE_MAX_PACKSTACK) { + if (cp->curpack < CPARSE_MAX_PACKSTACK-1) { cp->packstack[cp->curpack+1] = cp->packstack[cp->curpack]; cp->curpack++; + } else { + cp_errmsg(cp, cp->tok, LJ_ERR_XLEVELS); } } else if (cp_str_is(cp->str, "pop")) { if (cp->curpack > 0) cp->curpack--; diff --git a/test/tarantool-tests/lj-1114-ffi-pragma-pack.test.lua b/test/tarantool-tests/lj-1114-ffi-pragma-pack.test.lua new file mode 100644 index 00000000..e5642828 --- /dev/null +++ b/test/tarantool-tests/lj-1114-ffi-pragma-pack.test.lua @@ -0,0 +1,44 @@ +local tap = require('tap') + +-- Test file to demonstrate LuaJIT incorrect parsing of `#pragma` +-- directive via FFI. +-- See also: https://github.com/LuaJIT/LuaJIT/issues/1114. + +local test = tap.test('lj-1114-ffi-pragma-pack') +local ffi = require 'ffi' + +test:plan(2) + +-- `cp->packstack` is the array of size `CPARSE_MAX_PACKSTACK` +-- (7). Before the patch, `cp->curpack` is checked to be less than +-- `CPARSE_MAX_PACKSTACK`, but then `cp->packstack` is accessed at +-- `cp->curpack + 1`, which is out of bounds, so `cp->curpack` +-- value is overwritten. +-- As a result, the incorrect pack value (1) is chosen after pop. +-- After the patch, the error is thrown in the case of overflow +-- (instead of rewriting the top pack slot value), so we use the +-- wrapper to catch the error. +local function ffi_cdef_wp() + ffi.cdef[[ + #pragma pack(push, 1) + #pragma pack(push, 1) + #pragma pack(push, 1) + #pragma pack(push, 1) + #pragma pack(push, 8) + #pragma pack(push, 8) + #pragma pack(push, 8) + #pragma pack(pop) + struct aligned_struct {uint64_t a; uint8_t b;}; + ]] + + -- Got 9 in case of buffer overflow. + return ffi.sizeof(ffi.new('struct aligned_struct')) +end + +local err, msg = pcall(ffi_cdef_wp) + +test:ok(not err, 'the error is thrown when couner overflows') +test:like(msg, 'chunk has too many syntax levels', + 'the error message is correct') + +test:done(true) -- 2.42.0
next reply other threads:[~2023-11-08 8:45 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-08 8:40 Sergey Kaplun via Tarantool-patches [this message] 2023-11-08 18:39 ` Igor Munkin via Tarantool-patches 2023-11-08 18:59 ` Maxim Kokryashkin via Tarantool-patches 2023-11-09 5:57 ` Sergey Kaplun via Tarantool-patches 2023-11-23 6:31 ` Igor Munkin via Tarantool-patches
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